Pump structure



July 31, 1945. w. PAINTER PUMP STRUCTURE Filed April '7, 1941 2Sheets-Sheet 2 INVENTOR -Fog- 1 14 Pal/2Z6)? BY v/zu,

ATTOR Patented Jul -31,4945

g PQIIDS'IBUOTUli-E; ,Boy W. Painter, Detroit, Mich, to'

Gerotor May Company, Baltimore, Md, a corporation of DelawareApplication April 7-, 1941, s rial No. mass This invention relates tofluid mps and e ticulariy to pumps of the rotating positive--displacement type. the principal object being the pro- 4 (cl. ins-1'26)with means for driving visionof a pumpstructureofthistypethhtissimple inconstruction and efiicient in operation.

Qbjectsof the invention include the provision of a pumpstructure'embodying a rotatable pumping element and including a movableend wall or member associated with the rotatable element and constantlyurged towards contact therewith by yieldable means, whereby whenthe-pump is dry andiunprimed a zero clearance y be established betweenthe rotatable element and walls at the opposite ends thereof, themovable wall being movable away from the-pump element upon the.presenceofadesirediiuidpressureinthepump chamber whereby to provide arunning clearance during operation but not sumcient clearance to permita sufiicient amount of fluid to by-pass between the inlet andoutletsides of the pump bethe plate member and the provision of aconstruction as above described in which axial. movement of the-platemember is limited to an extent insufficient to. permit an amount ofleakage between the inlet and outlet sides of the pump chambersuilicient to materially interfere with the desired operation of thepump inservice, together with a by-pass between the inlet and outletsides of vthe pump chamber and a pressure relief valve controlling theflow of fluid through the by-pass.

The above being among'th'e objects of the present invention the sameconsists in certain novel features of construction and combinationsof-parts to be hereinafter described with reference to the accompanyingdrawings, and then claimed, hav- 'ing the above and other oblectsinview.

In the accompanying drawings which illustrate suitable embodiments ofthe present invention tween thepumping element and the movable wall tomaterially affect the operation of the pump in service; the provision ofa pump as above described including a ,by-pass between the inlet and theout-'- and in which like numerals refer to like parts throughout theseveral diflerent views,

Fig. 1 is a vertical sectional view taken axially through a pumpstructure embodying the present invention, illustrating the same asbeing mounted let sides of the pump together. with -a springpressedpressure relief' valve in the by-pass for limiting the mammum pressurecapableof being built .up by the pump; the provision of a pump structure.as above described in which the rotating pumping means comprisesapairof rotating elements one surrolmding the other and provided withinterengageable tooth-like elements; and the I provision of a pumpstructure as above described in which the drive shaft is projectedthrough one side of the pump housing-and a passage isconnectedwththespacesurroimding'theshaftand with the suction side of thepump whereby to p11 vent \mdesirable escap from the pumphousing. e

Other obiects of the invention include the provision of a pump structureincluding a'housing providing acharnber having an inlet and an outletand pumping means in the'chamber comprising a pair or rotatable pumpelements one of which surroundsthe other andbothofwhlchareproone-end ofeach of the elements adapted to en-.gageoneendwallofthechamberandtheplate member being arranged inoverlying relationship :with respectto the opposite ends of the pumpelements, the plate member being rotatable and being drivingly connectedto the outer or the pumpeiemeats and being movable axially of saidchamber and constantly urged by yleidable means towards of iiuidalongthe shaft 4 5 vided with interenmeable tooth-like iii-elections.

. Hon-18.8.

upon the end plate of an electric generator or the 2 is a verticalsectional view taken transversely through thepump structure shown inFig. 1 as onthe line 2-! thereof;

mg. a is a vertical sectional view taken trans versely through the pumpstructure shown in Fig;

1 asonthe line 3-4 thereof;

Fig. 4 is a frasmentarysectional-view taken axially through thestructure the line 4-4 thereof; 'Fig. 5 is a fragmentary horizontalsectional view taken on'theline I-l ofFig.8 andillustrating the shape ofthe inlet and outlet ports for the pump;

Fig. 6 is aview similar to Fig. 1 but illustrating a modified form ofconstruction; Fig. 7 is a vertical sectional viewtak'en transshowninl'iglason versely through the pump structure shown in Fig.

6 on the line 1-! thereof.

Pig. 8 isaview similar to Fig. l and illustrating a mrther modified formof construction; and.

Fig.3 is a vertical sectional view taken on the In the broader aspectsthe present invention is capable of use in connection with various typesof rotatable pumps of the positive displacement and where the languageof the claims so permit they are to be interpreted in this broad sense,

The invention is, however, particularly adapted engagement t t pumpelement. mu or use in connection with those types of positive outermembers having interengageable tooth elements. One such type of pump isillustrated in United States Patent No. 1,682,563, issued August 28,1928 to Myron F. Hill on Internal rotor, and accordingly such type ofpump structure is illustrated in the drawings by way of explanation.

It will be appreciated that the pump of the present invention may bemounted in any suitable location and driven in any suitabl manner, butfor the purpose of description it is shown in the accompanying drawingsas being mounted upon the end plate in of an electric generator havinga' shaft i2 and an armature it, this providing a desirable mountingparticularly where the pump is to be employed as a, fuel or oil pump ofan internalcombustion engine employed in a motor vehicle, boat or thelike. In such case the end plate I 0 is provided with a boss ll; ofsubor other sealing means between them. The supas the two elements 80and 52 rotate in a counterclockwise direction as viewed in Flss. 2 and3, the rolling engagement between the two elements creates successivechambers in the direction of rotation of the two elements which chambersincrease in volume from the lower portion of the pump to the top deadcenter position as illustrated in Fig. 2 and then decrease in volumetoward the bottom dead center position, the fluid being drawn into thesechambers during their expanding movements and being positivelydischarged therefrom during the contracting movement thereof. For thepurpose of feeding fluid to these chambers and for the purpose ofreceiving the discharge therefrom the valve port member 22 has a pair ofkidney-shaped ports formed in its inner face as illustrated in Figs. 3,4 and 5,

the port 58 being the inlet port and the port I being the outlet port.Transversely extendingpassages 82 and it connect the ports is and 60,respectively, with the exterior face of the member 22 at which pointsuch passages are provided with suitable connections 86 and 68,respectively, connecting these es with a suction line ll porting memberI 8 is provided with two or more ears or flanges 28 b means of which thepump is secured to the-end plate Ill-by means of screws such as 28,preferably with the inter-position of a gasket such as-sli between .themember is and the end surface of the boss l8 of the plate I II.

As indicatedin Fig. 1 the boss is is provided with a pocket 32 formedtherein below the shaft i2 and connected b a passage "with a recess 38surrounding the shaft l2 formed in the inner face of the plate IIIaround the shaft l2. An oil guard 38 protects the inner end of thisrecess and an oil throw off ring 40 is formed on the shaft in therecess. Any oil trying to escape along the shaft. I2 is thrownoff by thering ll into the,

recess 35 and then flows through the passage 34 into the chamber orpocket 32 the outer face of which is closed by the member l8. An opening42 in the cooperating ear 26 of the member [8 then' permits escape ofthis oil to the outside.

The member 20 is provided with a cylindrical opening 45 therethrough andwhich opening is I lined by 8 suitable cylindrical wear ring 48 Withinarrangement being such that-the teethof the inner one are at all timesin engagement with the outer element. It will be noted from an in-"spectlon of Fig. 2 that the inner element I2 is fixed against relativerotation concentrically to the shaft l2 while the outer element 50 ismounted to rotate in the ring ll about an axis eccentric with theaxis-of rotation of the inner member. For complete details of the methodof operation of these elements reference may be had, to the Hill PatentNo. 1,682,563 previously mentioned.

The essential thing to understand in connection and discharge line 12,respectively.

As illustrated best in Fig. 4 the axially outer .face of the port'member 22 is provided with a central pocket I4 therein connected by apassage 16 with the outlet port ill. An annular rib ll formed on theaxially outer face of the member 22 around the pocket 14 provides a seatfor a pressure relief valve 80. The pressure relief valve is providedwith a short stem portion 82 which is slidably receivedfor guidingmovement within the cylindrical boss 84 formed centrally of the sheetmetal cover member 24 which is sealed to the axially outer face of theport member 22.

Bolts 86 which extend through the cap 24, port member 22 and chambermember 20 and thread into the supporting member is and suitable gasketsinterposed between the mating surfaces ofthese parts when employed,serve to maintain the assembled relationof all of these parts. A coilspring a partially received within a central opening 90 in the stemportion 82 of the valve I is maintained under compression between theouter wall of the boss '84 and the inner end of the opening 00 andconstantly urges the valve II I -itsseat and permits' liquid as beby-passed from the inlet port ll thereby and through the port I!directly to the inlet II. The valve 80 thus provides a means forlimiting the maximum pressure capable of being built up by the pump, and

by employing a spring "of suitable weight the maximum discharge pressuremayb suitably controlled as will be appreciated It will be appreciatedfrom the fact that the axis of rotation of the inner pump element I2 iseccentric tothe axis of rotation of the outer pump element II, thevarious parts making. up the pump housingmust be secured to the plateII- with the inner pump element 82 concentric with the shaft l2 and thepumping chamberformed within the sleeve ll with its axis eccentric withthe type of pump structure shownis that II with the shaft42. Thatportion of the shaft l2 projecting outwardly beyond'the end of the holslrerersbi nmreumesindismeterumda' cated at I up to approximately the faceof the inner pumping element, 52 and is then further reduced in diameteras indicated at I02 for reception of the inner element 52. For thepurpose of providing a driving connection between the portion I02 andthe inner element 52 opposite sides of the portion I02 are flatted oil,as indicated in Fig. 2, and the inner element 52 is provided with' asimilarly shaped opening for reception thereof. While the fit betweensuch opening and the portion I02 of the shaft I2 is necessarily a closefit in order toproperly maintain the position of the element 52with'respect to the element 50,- a slight amount of axial movement ofthe element 52 on the portion I02 is preferable for reasons which willhereinafter be more apparent.

The lefthand face of the supporting member I8 as viewed in Fig. 1 isprovided with a recess I04 surrounding the portion I00 of the shaft I2and in this recess is received a suitable type of shaft seal element I05 which serves to prevent the escape of fluid to the left along theshaft I2 from the pump. Space is left between the bottom of the recessI04 and the seal I06 and this space is connected by a passage I00 whichextends through all three members I 0, and 22 with the space between themember 22 and the cover 24 and, therefore, communicates through thecover 24 and passage 92 with the suction port 58 of the pump. By thismeans any leakage from the pump tending to travel to the left along theshaft I2. as viewed in Fig. 1, is returned to the suctionslde of thepump. and this feature in con- Junction with the seal I05 preventsleakage along the shaft I2 to the left of the seal I06.

As brought out in Fig. l the pumping elements 00 and 52 are of equalaxial dimensions and of less axial dimension than the axial dimension ofthe pumping chamber formed within the sleeve 48 between the opposedfaces of the members l8 and 22. In this respect the outer face of thesupporting member may be slightly recessed in concentric relation to thering member 40 if desired to increase the effective length of thepumping chamber formed within the member 08. The pumping elements 50 and52 are adapted to lie in substantial engagement with the cooperatingface of the port member 22 thus leaving a space between the pumpingelements and the op posed face of the supporting member I831 This spaceis partially fllled with a disc-like plate member IIO which is of anexternal diameter to be closely but axially slidably received within theopenings H8 and the lefthand face of the plate member H0.

The springs IIIi are relatively light in character so that when the pumpis rotated and the discharge pressure of the pump is exerted on therighthand face of the plate member IIO the springs II6 will yield andwill permit the plate member IIO to move to the left as viewed in Fig. 1away from the cooperating face of the elements 50 and 52. It will beappreciated from this, however, that if the plate member IIO waspermitted a suflicient amount of axial movement under such conditionsthe inlet port 58 would be connected to the discharge port '00 throughthe space thus providedbetween the plate member H0 and the pump elements50 and 52 to such an extent as to seriously interfere with the properoperation of the pump and would limit the maximum pressure which couldbe built up by the pump to that\ required to overcome the springs IIS bythe discharge pressure of the pump acting on the plate. IIO. However, inaccordance with this phase of the present invention the space betweenthe lefthand face of the plate member I I0 and the righthand face ofthesupporting member l8, as recessed in the particular constructionshown and the bottom of which recess constitutes the corresponding endwall of the pumping chamber in this case,. is of a desired limitedextent, the amount actually shown in the drawings being exaggeratedsimply for the purpose of illustration.

It will be appreciated that in operation it is not desirable that theends of the pumping elements 50 and 52 actually lie in metal-t -metalcontact the port member22 as such condition would result in too rapidwear between these parts. It is sleeve 48. It is centrally provided withan openare provided for constantly urging the. plate member IIO to theright as viewed in'Fig. 1 toward engagement with the opposed faces ofthepumping elements 50 and 52. While any suitable and suitably arrangedspring elements may be provided for this purpose, in the particularconstruction shown these comprise light coil springs II6 received inblind openings II8 equally angularly spaced about the righthand faceofthe supporting member I0 midway between the openings I I4.

The springs IIS are maintained undercompres sion between the bottoms ofthe corresponding pumped be present between such surfaces so as toobviate such wear. The amount of axial movement of the plate member H0is preferably such that when the same is subjected to the dischargepressure of the pump it will move inwardly or to the left as viewed inFig. 1 into contact with the cooperating face of the supporting memberI0 under which circumstances the pumping elements ,50 and 52 may shiftaxially of the shaft I2 to provide a desired amount of clearance betweentheir opposite ends and the surfaces opposing the same to permit adesired thickness of film of the fluid being pumped to maintain thepumping elements out of metal-to-metal contact with these surfaces. Theamount of such axial movement of the plate. I I0, however, whilesuflicient to' provide such film of fluid on either side of the. pumpingelements 50 and 52 is preferably-not sufficient to provide for asuflicientflowof fluid between the inlet and outlet sides of the pumpingchamber to materially affect thmumping characteristics of the pump.Where. the pump is designed to pump some thin liquid such as gasoline,for instance,under a maximum pressure of ten to fifteen pounds persquare inch, the permissible move- I under a low pressure. Thus whilethe plate member I I0 may move axially to provide clearance between itand the pumping elements and permit the pumping elements to move axiallyto provide clearance between them and the inner face of the port member22, this clearance is desirably insufllcient to have any material effectupon the pressure produced by and volume of fluid discharged by the pumpduring normal operation.

It will, of course, be appreciated that the axial dimension of thepumping chamber could be fixed and sufficient to provide the desiredamount of clearance on opposite sides of the pumpin elements 50 and 52as above described without the necessity of providing the axiallymovable plate member IIII. Under such conditions, however, when the pumpwas dry or unprimed and, therefore, filled with air, the leakage of airthrough such clearance between the inlet and outlet sides of the pumpmight seriously interfere with the ability ,of the pump to pick upliquid having a level materially below the pump and thus adverselyaffect the ability of the pump to prime itself. With the axially movableplate I I whenever liquid being operated upon by the pump is drainedfrom the pump and the pump is filled with air, then the springs II'6force the plat IIO into actual contact with the elements 50 and 52 andforce the elements 50 and 52 into actual contact with the inner face ofthe port member 22 and thereby positively eliminating all clearance atthe ends of the pumping elements and any possibility of leakage of airbetween the inlet and outlet sides of the pump chamber past theend facesof the pumping elements. It is this feature of the elements that isespecially valuable in helping the pump to quickly and readily primeitself when in a dry or substantially dry condition, andat the same timethe structure provides the necessary clearance between the ends of thepumping elements and their cooperating surfaces to eliminatemetal-to-metal frictional contact between them during normal operation,thereby providing a pump having long life in service.

In Figs. 6 and '7 a modified form of construction is shown whichincludes all of the features of the construction previously describedwith the exceptio that instead of driving the inner element of thepumping means the outer element thereof is driven. Accordin ly. all of'the parts in Figs; 6 and 7 which are identical to those illustrated inthe previous views are identified by the same numerals and such partsthereof as are modified are identified by the .same numerals bearings.prime mark. Accordingly, it will only be necessary to describe thoseparts of the construction in which any changes have been made.

In the construction shown in Figs. 6 and 7 the drive being throughtheouter pump element 50', the inner pump element ,52' is mounted forrotation upon a stub shaft I20 projecting to the left, as viewed in Fig.6, from the port member 22 and having its right end suitably fixed inthe port member 22. The interior of the sleeve 43, instead of beingarranged eccontrically with respect'to the axis of the shaft I2 asnecessitated in the first construction, is In this case arrangedconcentrically with such shaft in order to bring the outer pump element50' into concentric relation with respect thereto. In this case theplate member 0' has fixed thereto one or more outwardly projecting pinsI22 fixed with respect thereto and axially slldably received in openingsI24 formed in the inner face of the pumping element 50' in parallelrelation to the axis thereof. This construction provides a drivingengagement between the plate 0' and the outer pump element and yetprovides for axial movement between the plate member H0 and the pumpinto the same extent as in the first described construction.

In the construction shown in Figs. 6 and '7 the supporting member I8,corresponding with the supporting member I0 first described, is requiredto be made of a greater axial length. In this case it is provided with acentral bore I26 in the inner or lefthand portion of which a sealingelement I06 is received against an abutment I28 formed in the bore I26adjacent the lefthand end thereof as viewed in Fig. 6 so as to limitmovement of the seal in that direction. The shaft I2 in this case isprovided with an axial extension I30 centrally received by the seal I06and the righthand end of the extension I30 terminates in the bore I26and is provided with a diametrical slot I32 therein. The plate member H0is provided with an axial stub shaft portion I34 projecting inwardly orto the left as viewed in Fig. l which extension terminates in adiametrically disposed tongue I36 closely but axially slidably receivedwithin the slot I32. The inter-engagement of the slot I32 and tongue I36thus forms a driving engagement between the shaft I2 and the platemember H0 and yet provides for axial movement between them. In order toconstantly press the plate member 0' towards the pumping elements 50 and52', a coil spring I38 is provided in the bore I26 surrounding the shaftportions' I30 and I34 and is maintained under compression generallybetween the plate member I I0 and the seal I06. Becauseof the relativerotation between the plate member H0 and the seal I06, a plurality ofanti-friction thrust washers such as I40 are preferably provided betweeneach end of the spring I38 and the cooperating surfaces of the seal I06and plate member H0. The effect of the spring I38 is, of course,intended to be exactly the same as that of the springs H6 in the firstdescribed construction.

It will be observed that the construction illustrated in Figs. 6 and Ioperates in substantially the identical manner as the constructionillustrated in Figs. 1 to 5, inclusive, the main difference being thatin driving through the plate member IIO to the outer pumping element 50,with the particular construction of the pumping element shown, that isan inner one having four tooth-like projections 56 and an outer onehaving five tooth-like projections 54, the construction shown in Figs. 6and 7 will operate at a 20% higher speed and consequently will deliver20% eater flow of fiuid at the same rate of rotation of the drivingshaft than the construction first described.

A still further modification is illustrated in Figs. 8 and 9. Thismodification is identical to the construction shown in Figs. 6 and 7except that a port member I60 is employed to replace the port member 22,cover member 24 and associated elements, and except for the fact that inthis case the plate member 0' is permitted to have a greater amount ofaxial movement thereby to serve as a pressure relief valve. In otherwords the righthand or outer end of the supporting member I8 is in thiscase provided with a recess I52 into which the plate member IIO mayaxially move under the influence of the discharge pressure of the pumpto an extent sufficient to permit fluid to be by-passed from the \outletto the inlet sides of the pumping elements spring I30 will, of course,necessarily be a heavier i spring than the spring I33 employed in thecon elements for the same reasons and preferably gti-ucflo l t t in m gd 7, th spring 2,380,783 I88 being of sufllcient weight or strength torestrict the movement of the plate member H to that necessary to buildup the desired discharge pressure in the pump but yielding when thispressure is exceeded to permit by-pass of the fluid across the innerends of the pumping elements 50' and 52' to prevent the further buildingup of such pressure. Obviously with such construction it is unnecessaryto provide the pressure relief valve structure provided in the firstdescribed constructions and consequently the port member I50 is providedin its inner face with inlet and discharge ports 58 and 60',corresponding with the ports 58 and 60 previouslydescribed, and theseare connected to inlet passage 62 and outlet passage 64, respectively,leading to the outer end face of the member I50. The operation will, ofcourse, be apparent.

Having thus described my invention, what 1 claim by Letters Patent is: Y

1. In a fluid pump, in combination, ahousing having a chamber thereinand inlet and outlet passages communicating with said chamber, arotatable pumping means in said chamber, said pumping means being of adimension axially thereof smaller than the axial dimension of saidchamber, a plate member interposed between one end of said pumping meansand the corresponding end of said chamber and having a limited amount ofaxial movement therein suflicient to provide axial running clearance forsaid pump ing means in said chamber but insumcient to permit by-passingof fluid between the inlet and the outlet sides of said pumping means insumcient quantities to materially detract from the normal volume andpressure characteristics of the pump in service, readily yieldable meansurging said plate towards engagement with the corresponding face of saidpumping means, said housing having a by-pass between said inlet and saidoutlet passages, a spring pressed relief valve associated with saidby-pass passage subject to the discharge pressure of said pump forlimiting the maximum pressure capable of being built up by said pump onthe discharge side thereof, a shaft for driving said pumping means, saidhousing having a second chamber surrounding said shaft in axially offsetrelation with respect to the first mentioned chamber, sealing meansarranged between the walls of said second chamber and said shaft inaxially spaced relation with respect to said plate member, and saidhousing having a passageway communicating the space between said sealingmeans and said plate with said suction passage, said readily yieldablemeans being less than theaxial dimension of said chamber, a platenon-rotatably but axiallyslidably received in said chamber between oneend of said elements and the opposed end of said chamber, said platebeing limited in its axial movement to ,that sufllcient to provide axialrunning clearance for said pumping elements but less thancharacteristics of said pump, means forming a tact with said elements, aby-pass between said inlet and said outlet passages, a spring pressedrelief valve in said by-pass passage for limiting the maximum pressurecapable of being built up by said pump, and means for driving saidelements, said spring means yielding under a materially lower dischargepressure of said pump acting on said plate than that required to actuatesaid relief valve.

3. In a fluid pump, in combination, a housing having a chamber thereinand inlet and outlet passages communicating with said chamber, a pair ofrotatable pumping elements in said chamber, one of said elementsenveloping the other thereof and having internal tooth-like'elementsoperatively engaging external tooth-like elements of said envelopedelement, said elements being of equal axial dimension and the axialdimension thereof being less than the axial dimension of said chamber, aplate rotatably and axially slidably received in said chamber betweenone end of said elements and the opposed end of said chamber, said platebeing limited in its axial movement to that sufflcient to provide axialrunning clear-. ance for said pumping elements but less than thatrequired to materially affect the pumping action of said elements bypermitting flow of fluid between it and said elements from the outlet tothe inlet sides of said chamber, spring means con.- stantly urging saidplate toward contact'with said elements, a by-passbetween said inlet andsaid outlet passages, a spring pressed relief valve in said by-passpassage for limiting the maximum pressure capable of being built up bysaid pump, means forming a driving connection between said plate and theouter element of said pumping means comprising pin means arranged inparallelism to an axis of rotation of said pumping means forming adriving connection between the outer element of said pumping means andsaid plate, a rotatable drive shaft, and a connection between said plateand said drive shaft permitting relative axial movement of said platewith respect to said drive shaft, said spring means yielding under amaterially lower discharge pressure of said pump actingon said platethan that required to actuate said relief valve.

4. In a pump structure, in combination, a housing having a chambertherein and inlet and outlet passages communicating with said chamber,rotatable pumping means in said chamber of less axial dimension than theaxial dimension of said chamber and comp'rising a pair of rotatableelements one surrounding the other and having interengageable tooth-likeelements, a plate member in said chamber interposed between one end ofsaid pumping means and the opposed end wall of said chamber and having alimited amount of axial movement therein, spring meanscons'tantly'urging said plate member toward engagement with said pumpingmeans, the possible axial movement of said plate member being sufficientto provide axial running clearance for said pumping means .in saidchamber but less than that required to permit a sumcient flow of fluidbetween the inlet and outlet sides of said pumping means to materiallyaffect normal operating driving connection between said plate member andthe outer element of said pumping means 6 assonas comprising pin meansarranged in parallelism to an axis of rotation of said pumping meansforming a driving connection between the outer' element of said pumpingmeans and said plate member, a rotatable drive shaft, a connectionbetween said plate member and said drive shaft permitting relative axialmovement of said plate member with respect to said drive shaft, saidhousing having a by-pass therein between said inlet and said outletpassages, and a spring pres- 10 ROY W. PAINTER.

